public boolean isIntentAvailable(Context context, String action) {  final PackageManager packageManager = context.getPackageManager();  final Intent intent = new Intent(action);  List<ResolveInfo> resolveInfo = packageManager.queryIntentActivities(intent, PackageManager.MATCH_DEFAULT_ONLY);  if (resolveInfo.size() > 0) {  return true;  }  return false;
}

<intent-filter>  <action android:name="android.intent.action.MAIN" />  <category android:name="android.intent.category.LAUNCHER" />
</intent-filter>

private void loadApps() {           Intent mainIntent = new Intent(Intent.ACTION_MAIN, null);           mainIntent.addCategory(Intent.CATEGORY_LAUNCHER);             mApps = getPackageManager().queryIntentActivities(mainIntent, 0);       }

import java.util.List;
import android.app.Activity;
import android.content.Intent;
import android.content.pm.ResolveInfo;
import android.os.Bundle;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.GridView;
import android.widget.ImageView;
public class MyHome extends Activity
{         GridView mGrid;             @Override    public void onCreate(Bundle savedInstanceState) {           super.onCreate(savedInstanceState);                     loadApps();           setContentView(R.layout.main);           mGrid = (GridView) findViewById(R.id.apps_list);           mGrid.setAdapter(new AppsAdapter());       }        private List<ResolveInfo> mApps;  private void loadApps() {           Intent mainIntent = new Intent(Intent.ACTION_MAIN, null);           mainIntent.addCategory(Intent.CATEGORY_LAUNCHER);              mApps = getPackageManager().queryIntentActivities(mainIntent, 0);      }    public class AppsAdapter extends BaseAdapter   {           public AppsAdapter() {         }               public View getView(int position, View convertView, ViewGroup parent) {               ImageView i;                   if (convertView == null) {                   i = new ImageView(MyHome.this);                   i.setScaleType(ImageView.ScaleType.FIT_CENTER);                   i.setLayoutParams(new GridView.LayoutParams(50, 50));               } else {                   i = (ImageView) convertView;               }                   ResolveInfo info = mApps.get(position);              i.setImageDrawable(info.activityInfo.loadIcon(getPackageManager()));                   return i;           }                   public final int getCount() {              return mApps.size();           }               public final Object getItem(int position) {               return mApps.get(position);           }               public final long getItemId(int position) {               return position;           }       }
}

@Override 

public void onItemClick(AdapterView<?> parent, View view, int position,long id) {            ResolveInfo info = mApps.get(position);                          //该应用的包名            String pkg = info.activityInfo.packageName;               //应用的主activity类            String cls = info.activityInfo.name;                           ComponentName componet = new ComponentName(pkg, cls);                          Intent i = new Intent();              i.setComponent(componet);              startActivity(i);
}